In the field of image compression and image recognition, associative memories with a minimum distance search function have attracted attention. The associative memory stores R pieces of reference data each having a bit width W (W and R are natural numbers). When a data string (search data) is input, the associative memory searches the plurality of reference data pieces for the most similar data piece (having the shortest distance).
It is basic processing in pattern matching to find the most similar reference data to the input data string (see Non-Patent Document 1). Therefore, the minimum distance search associative memory is useful in information processing such as image compression and image recognition. The minimum distance search associative memory is for example disclosed in Patent Document 1. Furthermore, fully parallel associative memories having search capability for Hamming distance, Manhattan distance and Euclidian distance are disclosed by Patent Document 2 and Non-patent Documents 2 and 3.